1. Field of the Invention
The present invention relates to a method for manufacturing a light emitting device having a light emitting element over a substrate and a manufacturing system thereof. Specifically, the present invention relates to a method for manufacturing a light emitting device wherein a layer including an organic compound is to be a light emitting layer and a manufacturing system thereof.
2. Description of Related Art
In recent years, studies on a light emitting device having an EL element as a luminous element have intensified. In particular, a light emitting device using an organic material as an EL material has attracted an attention. The light emitting device is referred to as an organic EL display (OELD) or an organic light emitting diode (OLED).
Note that an EL element includes a layer containing an organic compound in which luminescence (Electro Luminescence) generated by applying an electric field is obtained (hereinafter, referred to as an EL layer), an anode, and a cathode. In luminescence emitted by an organic compound, there are fluorescence that generates when electrons return from a excited singlet state to a ground state and phosphorescence that is emitted when electrons return from a triplet excited state to a ground state. A light emitting device manufactured according to a deposition device and deposition method of the present invention is applicable to both kinds of luminescence.
Further, there are two kinds for forming the light emitting device: a method where an EL layer is formed between two kinds of striped electrodes provided so as to cross at right angles to one another (a simple matrix method), and a method where an EL layer is formed between a pixel electrode which are connected to a TFT and arranged in matrix and a counter electrode.
An EL element has a structure in which an EL layer is sandwiched between a pair of electrodes; generally, the EL layer has a laminated structure. Typically, the laminated structure, “a hole transporting layer/ a light emitting layer/ an electron transporting layer” proposed by Tang et al. of Kodak Eastman Company is generally known. The structure has extremely high luminous efficiency and is employed for almost all light emitting devices that are under development now.
Further, a structure in which a hole injecting layer/ a hole transporting layer/ a light emitting layer/ an electron transporting layer are laminated in order over an anode or a hole injecting layer/ a hole transporting layer/ a light emitting layer/ an electron transporting layer/ an electron injecting layer are laminated in order over an anode is also applicable. Fluorescent pigment and the like can be doped to the light emitting layer. Such layers may be formed by entirely using a low molecular weight material or by partly using a high molecular weight material to the part of the layers.
Further, a light emitting device has no viewing angle problems by virtue of its self-luminous property differently from a liquid display device. Thus the light emitting device is more suitable for using in the open air than the liquid crystal display device. Various types of usage of the light emitting device have been proposed.
In production lines of a liquid crystal display device, the size of a substrate tends to become larger year by year in order to reduce the production costs. Further, the number of display panels (the number of panel faces) manufactured per substrate has been increased.